Torsion dystonia is a hereditary neurologic disease affecting brain function in over 100,000 individuals in North America. Symptoms include uncontrollable muscle spasms, spastic dysphonia, contortions of the limbs, torticollis, and blepharospasm. There are no neurochemical or neuropathological clues as to the cause of this disease. Dystonia is inherited as an autosomal dominant condition in many ethnic populations, with a high incidence in Ashkenazic Jews. Our group has located a gene responsible for generalized dystonia in Jewish and non-Jewish families on human chromosome 9q32-q34 by linkage analysis. Here we propose a systematic, molecular genetic approach to identification of this dystonia gene. We will define the location of the gene as precisely as possible; construct a genetic and physical map of the 9q32-q34 region; and characterize transcribed sequences from this genomic region expressed in the brain. Additional affected families that show linkage to this region will be ascertained, and information will be summed across families to define the critical region (2-3 cM) containing the gene by tightly linked, flanking markers. The location of the disease gene will be further specified by co-inheritance of specific alleles for surrounding loci. Additional genomic clones will be identified in the critical region using somatic cell hybrids containing portions of human chromosome 9q, YAC clones, and 'walking" procedures. These genomic clones will be physically mapped by somatic cell hybrid panels; pulse field gel electrophoresis; and in-situ hybridization to metaphase chromosomes. New clones will be screened for repeat sequences to determine highly informative polymorphisms, and genetic distances will be established in large reference pedigrees. Genomic fragments will be evaluated for encoded sequences by testing for sequences conserved among species, by hybridization to RNA on Northern blots, and by probing cDNA libraries. Brain cDNAs will be characterized by sequencing and evaluated for a role in dystonia by hybridization to DNA from control and affected individuals to look for gross rearrangements and by comparison of coding sequences generated by PCR amplification. These studies will serve to generate a detailed map of human chromosome 9q32-q34, and to elucidate brain-expressed transcripts coded therein. Eventually this work will lead to identification of the dystonia gene and understanding of its function, which in turn should provide insight into the molecular etiology of this disease state and help in designing new therapies.